The Scottish National Party candidate for Gordon in Aberdeenshire has been called many things: arrogant, self-aggrandising and independence-obsessed to name a few. But Alex Salmond as selfless? That sounds downright counter-intuitive. Yet nine months on from announcing his resignation as first minister and leader of the SNP, Salmond’s decision to leave office looks likely to have a profound impact upon electoral and constitutional politics in the UK for the foreseeable future.

Let me back up a moment. When other academics and I were doing media interviews on behalf of the Centre on Constitutional Change during the referendum, we were well briefed that if there was a Yes vote, on no account were we to answer the question: “Does the prime minister have to resign?”

A Yes win was a real possibility. It was even considered (by some) as likely, which is why we were preparing for that question. What was never mentioned was the question in reverse: “If there is a No vote, would the first minister have to resign?” The broad assumption was that, irrespective of the outcome, Salmond would remain in office. It seemed foreseeable that he would only step down after he had served as the first leader of an independent Scotland.

So when Salmond called an “invitation only” press conference on September 19, few among those assembled expected him to resign. Nine months on, of course, the SNP has put the disappointment of the referendum defeat firmly behind it, quadrupled in size and is expected to topple (if not obliterate) Labour in Scotland on May 7.

The resignation effect

What Salmond did by resigning was to immediately associate the referendum defeat with himself. Moving the SNP from a fundamentalist to gradualist position in his first stint as leader during the 1990s had entailed the adoption of a referendum on independence as SNP policy, away from the previous position that a majority of SNP MPs would trigger independence. He had been one of the prime movers behind the strategy, and as such, the policy shift was tied to his leadership.

In the days following his resignation Salmond went further, announcing that a referendum was just one way in which Scotland could become independent. He even cited a unilateral declaration of independence as one possible method. In effect he was clearing the decks for his successor, providing a blank canvas for the party to start the next phase of its existence.

This allowed the “everything to everyone” thinking which had been a large part of the Yes campaign’s strategy during the referendum to apply to the SNP as well. The Yes campaign had been a broad church of support for independence: from left and right, business and unions, monarchists and republicans. Crucially this attracted new members to the party under the leadership of Nicola Sturgeon, members who perhaps would not have been attracted under Salmond.

It also attracted new voters through the perception that under Sturgeon’s leadership, the party would be able to deliver more upon the centre-left social democratic principles it had articulated during the referendum, since she has always been identified more with that wing of the party.

The final point is that Salmond left Sturgeon in charge. He did so because he trusted his deputy to make the step up. Her different style and willingness to co-operate with Westminster in ways her predecessor appeared unable to do has of course won her much admiration north and south of the border.

What if he was still there?

Admittedly, the SNP’s surge might have happened anyway. Disenchanted Yes voters would potentially have turned to the party as a means of furthering the case for independence. But the departure of the SNP’s long-term leader – a clear “Marmite” figure in British politics – has accelerated this trend.

In this light, Salmond’s decision to step down looks much more strategic than selfless. If the forecasts of a resounding victory come true on May 7 and Salmond is one of a group of 40 or 50 SNP MPs taking their places at Westminster, it may well be that his resignation is the one of the main reasons why.